Navy seeks guided deck-gun shell

Jun. 4, 2014 - 06:00AM
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The Navy is seeking a guided shell for the 5-inch deck gun on current cruisers and destroyers that would greatly extend range and potency. Here, the destroyer Mahan tests its 5-inch gun in a 2010 live fire exercise. (MC1 Daniel Gay/Navy)

The Navy wants to arm its cruisers and destroyers with shells-turned-missiles that would bring naval gunnery and the 5-inch deck gun into the age of the smart bomb.

The to-be-developed 5-inch shell should have twice the range of current shells used against land targets, ships and fast boats, according to a May 9 request for information. A spokesman for Naval Sea Systems Command stressed this was an opening salvo see what’s possible — not the start of a procurement process for such a shell.

“The Request for Information (RFI) is an important tool to pulse industry and help us understand what is in the realm of the possible as well as fiscally feasible,” Dale Eng said in an email Tuesday to Navy Times. “We’re interested to see what’s out there.”

In effect, the Navy is looking to arm its destroyers and cruisers with a smaller version of the Long-Range Land Attack Projectile to be fired from the state-of-the-art Zumwalt-class destroyers, said Christopher Harmer, senior naval analyst with the Institute for the Study of War.

The LRLAP is a 155mm shell fired from a gun barrel that is guided to its target by a rocket motor, giving it a range of 63 nautical miles, Harmer said in an email Wednesday to Navy Times. Once it leaves the barrel, the shell sprouts fins, which are controlled by a guidance section in the nose.

“The guidance section checks its current location, current trajectory, compares that to where it is supposed to go [the target], and makes adjustments in flight,” Harmer said. “The projectile is then actively guided to the [target], and impacts there. Basically no different than a Joint Direct Attack Munition.”

A guided 5-inch shell would give these advanced capabilities to the Navy’s current cruisers and destroyers, he said. Even in the age of missiles, the Navy still needs guns to destroy incoming missiles, destroy or deter enemy aircraft, and put a hole in larger ships.

But most of all, Navy ships need precision shells to pummel incoming small boats — Iran’s tactic of choice.

In the 1980s, the Iranian navy was decimated in engagements with the U.S. Navy, so the Iranians changed tactics, Harmer said. Now, the Iranians use small patrol craft and gun boats, which would be used by the hundreds in swarm attacks to overwhelm U.S. Navy. In April, an Iranian newspaper confirmed that the Iranians were building a mockup of the aircraft carrier Nimitz to be used to practice attacking U.S. aircraft carriers.

The Navy has a munition that would act against as a giant shotgun shell against such a swarm attack, but it has a limited range, Harmer said. A guided 5-inch shell would have a much longer reach and would stay intact for the entire flight.

“The most likely warhead would be an airburst blast fragmentation warhead with a proximity fuse,” he said. “Once the warhead gets near the small-boat swarm, it would sense proximity to the small boats and detonate in the air, spraying them with shrapnel.”